Saari, T. et al., “Emotional regulation system for emotionally adapted games”, Proceedings of FuturePlay 2005 conference, 13.-15.10. 2005, Michigan State University, USA relates to an approach to build emotionally adapted games based on a user-controlled emotional regulation system. It discloses a system design for including emotional regulation in a gaming engine. The engine continuously monitors user input. This input data is then processed and transferred to the layer that handles the game's internal logical state. The proposed emotional regulation can be implemented as a middleware system that runs in parallel to the actual game engine. The input processing layer of the game engine can receive a data flow of captured and pre-processed biofeedback sensor data. The real-time signal processing may consist of different forms of amplifying, filtering and feature selection on the biofeedback signals. This data flow may directly influence the state of the game world, or it can be used by the emotional regulation sub-module of the emotion feedback engine. This module consists of the rules of emotional balancing for different player profile types and game-related explicitly set preferences controlled by an “emotion knob”. The output of the emotional regulation engine may then be applied to various different levels of the actions of the game engine:    i) the logical state of the world may be re-directed,    ii) the actions of the synthetic agents may be controlled,    iii) the kinetics of the game may be altered and    iv) the rendering of the game world may be changed. The first two options are more related to high-level and story-related structures of the game, whereas the last two are more directly related to the selection of presentation of objects within the virtual environment.
A problem of the known system is that it is too simplistic to assume a player's emotional response based on physiological and performance-related parameters, because every player is different and players differ with respect to skills, preferences and emotional responses over time.